Method for driving an ultrasonic handpiece with a class D amplifier

Abstract

Method for controlling an ultrasonic handpiece of an ocular surgical system, such as a phacoemulsification system. First and second signal sources generate first and second drive signals. The first signal is at a first frequency and is used to drive a cutting tip of the handpiece with a first type of motion. The second signal is at a second frequency and is used to drive the cutting tip with a second type of motion. The different motions can be generated with different first and second frequencies. The first and second signals can be summed or combined and provided to a class D amplifier, the output of which includes multiple frequency components or multiple signals of different frequencies to drive the cutting tip in different directions at the same time, for example, with simultaneous longitudinal and torsional motions.

1 . A method for controlling an ultrasonic handpiece of a phacoemulsification surgical system, the method comprising: 
 providing a first signal at a first frequency and a second signal at a second frequency as inputs to a class D amplifier; and    driving the ultrasonic handpiece using the output of the class D amplifier, the output of the class D amplifier having at least two frequency components that simultaneously move a cutting tip of the ultrasonic handpiece in different directions.    
   
   
       2 . The method of  claim 1 , further comprising combining the first and second signals into a third signal, the third signal being provided as an input to the class D amplifier.  
   
   
       3 . The method of  claim 1 , wherein one of the first and second signals controls longitudinal motion of the cutting tip.  
   
   
       4 . The method of  claim 1 , wherein one of the first and second signals controls torsional motion of the cutting tip.  
   
   
       5 . The method of  claim 1 , providing the first signal to the class D amplifier comprising providing a first signal at a frequency of about 40 kHz to about 45 kHz.  
   
   
       6 . The method of  claim 5 , wherein the first signal controls longitudinal motion of the cutting tip.  
   
   
       7 . The method of  claim 1 , providing the second signal to the class D amplifier comprising 
 providing a second signal at a frequency of about 30-34 kHz.    
   
   
       8 . The method of  claim 7 , wherein the second signal controls torsional motion of the cutting tip.  
   
   
       9 . The method of  claim 1 , wherein the first signal controls a first motion of the cutting tip, the first motion defining a first plane, and the second signal controls a second motion of the cutting tip, the second motion defining a second plane, wherein the first and second motions are different from each other and the first and second planes are different from each other.  
   
   
       10 . The method of  claim 9 , wherein the first motion is longitudinal motion, the first plane is defined by a line corresponding to longitudinal motion, the second motion is torsional motion, and the second plane is defined by a plane of torsional motion.  
   
   
       11 . The method of  claim 9 , wherein the first and second planes are substantially perpendicular to each other.  
   
   
       12 . The method of  claim 1  being performed without switching between amplified first and second signals.  
   
   
       13 . The method of  claim 1 , providing the first signal and providing the second signal comprising providing first and second sinusoidal signals as inputs to the class D amplifier.  
   
   
       14 . A method for controlling an ultrasonic handpiece of a phacoemulsification surgical system, the method comprising: 
 providing a first signal at a first frequency to a class D amplifier, the first signal controlling longitudinal motion of a cutting tip of the ultrasonic handpiece;    providing a second signal at a second frequency to the class D amplifier, the second signal controlling torsional motion of the cutting tip;    driving the handpiece with an output of the class D amplifier so that the cutting tip of the handpiece moves with combined longitudinal and torsional motions.    
   
   
       15 . The method of  claim 14 , further comprising combining the first and second signals into a third signal, the third signal being provided as an input to the class D amplifier.  
   
   
       16 . The method of  claim 14 , providing the first signal to the class D amplifier comprising providing a first signal at a frequency of about 40 kHz to about 45 kHz, the first signal controlling longitudinal motion of the cutting tip.  
   
   
       17 . The method of  claim 14 , providing the second signal to the class D amplifier comprising providing a second signal at a frequency of about 30-34 kHz, the second signal controlling torsional motion of the cutting tip.  
   
   
       18 . The method of  claim 14  being performed without switching between amplified first and second signals.  
   
   
       19 . The method of  claim 14 , providing the first signal and the second signal comprising providing first and second sinusoidal signals as inputs to the class D amplifier.  
   
   
       20 . A method for controlling an ultrasonic handpiece of a phacoemulsification surgical system, the method comprising: 
 providing a first sinusoidal signal as an input to a class D amplifier, the first sinusoidal signal being at a frequency of about 40 kHz to about 45 kHz and controlling longitudinal motion of a cutting tip of the ultrasonic handpiece;    providing a second sinusoidal signal as an input to the class D amplifier, the second sinusoidal signal being at a frequency of about 30-34 kHz and controlling torsional motion of the cutting tip;    amplifying the first and second sinusoidal signals with the class D amplifier; and    driving the ultrasonic handpiece with the output of the class D amplifier so that the cutting tip moves with longitudinal and torsional motions at the same time.    
   
   
       21 . The method of  claim 20 , further comprising combining the first and second signals into a third signal, the third signal being provided as an input to the class D amplifier.  
   
   
       22 . The method of  claim 20  being performed without switching between amplified first and second signals.  
   
   
       23 . A method for controlling an ultrasonic handpiece of a phacoemulsification surgical system, the method comprising: 
 providing a first signal and a second signal as inputs to a class D amplifier, the first and second signals being different frequencies;    driving the handpiece with an output of the class D amplifier, wherein the class D amplifier switches between a first output at a first frequency corresponding to the first input and a second output at a second frequency corresponding to the second input to move the cutting tip in different directions at different times.